Sacrificial Vanadium Leaching Triggers Defect‐Rich High‐Valent Nickel Centers for Selective Seawater Oxygen Evolution

Comprehensive Summary Sluggish oxygen evolution kinetics and chloride‐induced corrosion remain critical barriers to the development of efficient anode catalysts for seawater electrolysis. Here, we propose a defect‐engineering strategy based on sacrificial vanadium(V) doping to construct a disordered NiFe layered double hydroxide ( d ‐NiFe(OH) x ) nanosheet electrocatalyst. During electrochemical activation, V is rapidly leached, inducing the in situ formation of abundant non‐metallic defects and lattice disorder. Experimental results, in‐situ characterizations combined with density functional theory (DFT) calculations reveal that the disordered structure promotes the formation and stabilization of catalytically active, defect‐rich high‐valent NiOOH phases, enhances the adsorption of OH – adsorption and suppress Cl – ‐ induced side reactions, and activates lattice oxygen participation in the OER process, thereby ensuring long‐term catalytic activity during seawater OER. As a result, the catalyst achieves an industrial‐level current density of 1.0 A·cm –2 at 1.55 V in alkaline seawater and maintains excellent stability over 160 h, with a hydrogen production cost as low as $1745 per ton. This work offers a theoretical basis for designing efficient and corrosion‐resistant OER catalysts for seawater electrolysis.